Sexual dimorphism in white and brown adipose tissue with obesity and inflammation

Obesity and its associated comorbidities remain at epidemic levels globally and show no signs of abatement in either adult or child populations. White adipose tissue has long been established as an endocrine signalling organ possessing both metabolic and immune functions. This role can become dysregulated following excess adiposity caused by adipocyte hypertrophy and hyperplasia. In contrast brown adipose tissue (BAT) is only present in comparatively small amounts in the body but can significantly impact on heat production, and thus could prevent excess white adiposity. Obesity and associated risk factors for adverse metabolic health are not only linked with enlarged fat mass but also are dependent on its anatomical deposition. In addition, numerous studies have revealed a disparity in white adipose tissue deposition prior to and during the development of obesity between the sexes. Females therefore tend to develop a greater abundance of femoral and gluteal subcutaneous fat whereas males exhibit more central adiposity. In females, lower body subcutaneous adipose tissue depots appear to possess a greater capacity for lipid storage, enhanced lipolytic flux and hyperplastic tissue remodelling compared to visceral adipocytes. These differences are acknowledged to contribute to the poorer metabolic and inflammatory profiles observed in males. Importantly, the converse outcomes between sexes disappear after the menopause, suggesting a role for sex hormones within the onset of metabolic complications with obesity. This review further considers how BAT impacts upon on the relationship between excess adiposity, gender, inflammation and endocrine signalling and could thus ultimately be a target to prevent obesity. (c) 2014 Elsevier Inc All rights reserved.